naginterfaces.library.blas.dspmv

naginterfaces.library.blas.dspmv(uplo, alpha, ap, x, beta, y=None)[source]

dspmv computes the matrix-vector product for a real symmetric matrix stored in packed form.

For full information please refer to the NAG Library document for f06pe

https://www.nag.com/numeric/nl/nagdoc_28.5/flhtml/f06/f06pef.html

Parameters
uplostr, length 1

Specifies whether the upper or lower triangular part of is stored.

The upper triangular part of is stored.

The lower triangular part of is stored.

alphafloat

The scalar .

apfloat, array-like, shape

The symmetric matrix , packed by columns.

xfloat, array-like, shape

The -element vector .

betafloat

The scalar .

yNone or float, array-like, shape , optional

The -element vector , if need not be set.

Returns
yfloat, ndarray, shape

The updated vector .

Raises
NagValueError
(errno )

On entry, error in parameter .

Constraint: or .

(errno )

On entry, error in parameter .

Constraint: .

(errno )

On entry, error in parameter .

Constraint: .

(errno )

On entry, error in parameter .

Constraint: .

Notes

In the NAG Library the traditional C interface for this routine uses a different algorithmic base. Please contact NAG if you have any questions about compatibility.

dspmv performs the matrix-vector operation

where is an real symmetric matrix stored in packed form, and are -element real vectors, and and are real scalars.